In a conventional electromagnetically driven punch press, such as shown in the Doherty U.S. Pat. Nos. 3,709,083, 4,022,090, 4,056,029 and 4,135,770, the upper one of the two opposed tooling components is driven vertically downwardly during the power stroke, and the lower tooling component remains stationary. Thus, there is a large downward impact occurring against the lower tooling component at the instant when the fast-moving upper tool impacts down upon the material to be formed between the upper and lower tooling. For example, the lower tool is a die and the upper tool is a punch which impacts down against a strip of steel material for punching finished pieces, such as washers, out of the steel strip.
As a result of such large downward impacts occurring against the lower tool in a conventional punch press, it is necessary to mount the whole punch press on a strong and massive work table, so as to be able to withstand the large mechanical shocks and vibrations being transmitted from the punch press down into its supporting work table. Moreover, it is necessary to provide strong flooring in the manufacturing plant where the punch press is operating so as to be able to withstand the heavy loading and mechanical stresses being imposed on the building day-after-day where the punch press is operated.
Furthermore, in spite of providing a strong massive work table and in spite of providing a strong factory floor, there is a disturbing "whomp" or "thump" which is transmitted repeatedly throughout the manufacturing plant and which can be felt by occupants of the building regardless of whether they are standing or sitting. Consequently, it is usual practice to locate punch presses in a remote area in a building or in a separate building so that the frequent "whomp" or "thump" does not unduly disturb other workers and office personnel.
It is to be appreciated that such mechanical shocks and vibrations which are disturbing to occupants of a building indicate that a relatively large amount of wasted energy is being transmitted from the punch press into its supporting work table and into the building structure. In other words, conventional punch presses are relatively inefficient machines. While they are performing their intended work on the material in the punch press, they are also performing wasteful work in shaking work tables, floors and walls of the buildings in which they are operating. Such wasteful work in shocking and shaking buildings tends to deteriorate buildings more rapidly than normal aging and is disturbing and possibly is detrimental to human beings who might be subjected to extended periods of nearby exposure to convention punch presses.
As a further comment about the problems caused by conventional punch presses, it is helpful to think about a piano or other stringed instrument. The majority of the sound which issues from a piano or from another stringed instrument does not come from the vibrating string itself. Rather, the major portions of the sound energy are radiated from a sounding board or sounding box which is mechanically connected to a vibrating string so as to be forced to vibrate with the string. The relatively large area of a vibrating sounding board or box couples well with gaseous air and is an efficient transmitter of sound energy into gaseous air whereas a vibrating string itself has a relatively small area and does not efficiently couple with the air and thus by itself does not transmit much sound energy into air. Similarly, the tooling itself and material to be formed in a punch press have a relatively small area a compared with the frame of the punch press plus the work table on which it is mounted, plus the floor and walls of the building in which it is operating.
Therefore, in my view, the major energy content of the very loud, disturbing noises produced by operating a conventional punch press is coupled to the air by and is radiated (broadcast) into the air from the punch press frame, from its work table or platform and from floor and walls of the room where it operates.
Conversely, in my view, only a relatively small proportion of the very loud total noise energy is radiated into the air by the tooling and material themselves. My experiments with a prototype set-up embodying the present invention have shown that the noise level in a room is reduced by about twenty decibels by employing a horizontally-oriented, opposed motion, momentum-balanced-at-impact punch press embodying the present invention, as compared with a conventional vertical punch press of the same tonnage rating.